A non-immunogenic biocompatible macromolecular molecular membrane composition is preferably substantially insoluble in bodily fluids, thus, non-biodegradable. Yet, it is also preferably suitable for contact with body fluids in or on the body. Ideally, such membrane composition has all or some of the following characteristics:
1. The membrane composition should avoid inducing undesirable reactions in the body (such as blood clotting, tissue death, tumor formation, allergy reaction, immune response or an inflammatory reaction). PA1 2. The membrane composition should have desirable physical properties (such as strength, elasticity, permeability, and necessary flexibility). PA1 3. The membrane composition should also be purified, fabricated, and sterilized easily. PA1 4. The membrane composition should be able to maintain its physical properties and functions during the time the membrane composition remains implanted in or in contact with the host body.
While there are biocompatible macromolecular skin graft, or skin substitute compositions in the literature, an impediment for in vivo implantation (both cutaneously and in any degree more internal than cutaneous, e.g., subcutaneous or intraperitoneal application) of biocompatible implants is lack of reliability. Another deficiency of these implants is that they are often not retrievable after implantation. This deficiency is significant, particularly when combined with yet a further deficiency of these implants, namely that they can lose physical properties. For instance, implants made from biodegradable materials degrade over time and thereby induce a local or a systemic immune response in a host system. Further, another deficiency of implants is the difficulty to monitor and inspect such implants.
A number of approaches have been taken to improve the biocompatibility of implantable items. One approach was to prevent undesirable protein adhesion by providing a biomaterial with a low polarity surface, a negatively charged surface, or a surface coated with biological materials such as enzymes, endothelial cells, or proteins. Another approach was to coat solid surfaces with heparin, albumin, or streptokinase to enhance thromboresistance. However, these approaches have failed to teach or suggest the preferably covalent bonding of the present invention or the binding agent of the present invention, or the methods of making and using the invention including the pouch embodiments on structures.
Several researchers have proposed different approaches to protecting islet tissue from host attack after transplantation; these included encapsulation of islets in different materials such that insulin may be secreted but the beta-cells in the islet tissue will be immunologically isolated from the host. Polysaccharides have been proposed to form membranes, as is the case of agarose, by Howell, Ishaq and Tyhurst (Journal of Physiology 324, 20-21, 1982) or alginate, by Tze and Tai (Transplantation 33, 563-564, 1982). Search of the more recent literature indicates that the effort to develop new membrane materials for cell encapsulation for implants keeps a strong and steady pace. These include synthetic poly-acids and poly-bases (Bader et al., 1988 Eur. Pat. App. EP 280,155), gelatin and polyamino acids (Young et al., Biopharm 2, 34, 36, 38, 40-46, 1989) as well as different polysaccharides; chemically modified dextran, to form poly-ionically bonded capsules (Lim and Hall, 1988, PCT Int. Appl. WO 88 00, 327), entrapment in alginate followed by stabilization with poly-lysine and alginate (Chang and Wong, 1992, U.S. U.S. Pat. No. 5,084,350, as well as a combination of chitosan and carboxy-methyl cellulose to form capsules of controlled permeability (Shioyo and Hirano, 1990, U.S. Pat. No. 5,089,272). A recent review by Mikos et al. (Biotechnol. & Bioeng. 43, 673-677, 1994) discusses other alternatives, all with emphasis on synthetic materials as membrane components.
On the other hand, recent work bearing on regeneration of skin in culture has pointed out the important role of GAG's in the process, in studies where mixtures of collagen and GAG were used to support it (Murphy et al., Lab. Invest. 62, 305-313, 1990; Yannas et al., Polym. Mater. Sci. Eng. 62 801-803, 1990). Along the same line, but coming from another direction, keratinocytes and fibroblasts grown on a nylon mesh produced a dermal-like matrix containing heparan sulfate proteoglycans (Slivka et al., J. Invest. Dermatol. 100, 40-46, 1993).
These works, that show the importance of the extracellular matrix components in the normal development of the skin system, support the basis of our invention, that foreign membranes lined or structured with GAG's may constitute ideal materials for devices aiming at transplantation of cells or tissues of human or animal origin, with the purpose of treating or controlling disease. Their surfaces will contain critical elements for successful interaction with the host organism. Although GAG's occur in the organism mostly linked to proteins, as proteo-glycans, it has been demonstrated that the protein part only is immunogenic; the glycosaminoglycan component is not immunogenic by itself (Hirschmann and Dziewiatkowski, Science 154, 393-395, 1966; Loewi and Muir, Immunology 9, 119-127, 1965).
The extent of the interest in discovering the best way to use islets in transplantation is given by two recently published papers, one dealing with storage and preservation of islets (Jindal and Gray, Transplantation 57, 317-321, 1994) and the other with the action of prednisone on the islet autograft function (Rodrigues Rilo et al., Transplantation 57, 181-187, 1994). However, none of this work teaches or suggests the pouch system of the present invention where in cellulose macromolecular membrane is bound with GAG, formed into a pouch and cells are inserted into it.
Likewise, species within the term glycosaminoglycan ("GAG") may have been mentioned in connection with compositions, but these compositions are unlike the present invention, and, so too are the prior approaches to improve biocompatibility.
For instance, Guire, U.S. Pat. Nos. 4,979,959 and 5,263,992, relate to materials having a surface coating which is a covalently bound biocompatible agent. While cellulose is included in a long list of allegedly possible materials and heparin is included in a long list of allegedly possible agents, there is no teaching or suggestion to specifically select the combination of cellulose and heparin or, any working example thereof. Further, Guire's reagents require activation by light in order for the reaction to proceed. A "dark room" type of reaction with subsequent light activation is thus required; and, this is complicated and presents economic deficiencies and industrial scale-up or other preparation or utility problems. In contrast, the present invention specifically calls for a cellulose membrane having glycosaminoglycan covalently surface bound via a linker molecule, a binding agent bound without any need for light activation. For instance, conditions of pH and temperature may be favorable for binding, without resort to any complicated photoreaction. Consequently, Guire, either individually or in any combination, contains no teaching or suggestion of the present invention or, of the pouch embodiments or methods of the invention.
Tsilibary, U.S. Pat. No. 5,152,784, is directed to a polypeptide which represents a fragment of the .alpha. 1 chain of type IV collagen which is a promoter for binding heparin to synthetic substrates in order to facilitate cellular adhesion or growth surface. However, Tsilibary's polypeptide contains a glycoprotein which has been demonstrated as a source for eliciting an immune response. Thus, Tsilibary is contrary to, and, either individually or in any combination, fails to teach or suggest the present invention. See, Hirschman and Dziewiatkowski, Science 154, 393-395, 1966; Loewi and Muir, Immunology 9, 119-127, 1965. Further, macromolecular structures and uses therefor as herein taught are not disclosed or suggested in Tsilibary.
Lim, U.S. Pat. No. 4,409,331, relates to a method of using polysaccharides to encapsulate islet cells which secrete insulin. However, there is no teaching or suggestion in Lim of macromolecular structures or, of the binding agent or linker molecule in the present invention. Further, Lim does not teach or suggest encapsulating cells nutrient or anything else for secretion in vivo or in vitro or use growing media or as a pouch. And therefore, Lim, either individually or in any combination fails to teach or suggest the present invention.
Yannas, et. al., U.S. Pat. No. 4,060,081, is directed to a two-layer membrane for use as a synthetic skin. The first layer is formed from crosslinking composites of collagen and a mucopolysaccharide and the second layer is formed from a nontoxic synthetic polymers such as silicone resins, polyacrylate, or polymethacrylate esters or their copolymers, and polyurethane. The present invention does not involve crosslinked composites of collagen or of glycosaminoglycan. Brazilian Patent No. 38404937 relates to a cellulose pellicle for treating skin injuries but, the pellicle does not have GAG bound at or to its surface. Accordingly, Yannas and Brazilian Patent No. 38404937, either individually or in any combination, fails to teach or suggest a non-immunogenic macromolecular cellulosic membrane having GAG covalently bound thereto through a linker molecule. As in the present invention, or the structures or embodiments thereof and uses therefor of the present invention.
Meisner, et. al, U.S. Pat. No. 4,585,754, relates to orally administering insulin formed from reacting it with chondroitin or, more generally to stabilizing a pharmaceutically active substance to produce an ester and/or amide derivative thereof. Nimni, et al., U.S. Pat. No. 4,378,224, relates to crosslinking a GAG (not necessarily preferred in the present invention, see infra) and covalently binding it to an allograft or heterograft. Barbucci, et al., U.S. Pat. No. 4,944,767 relates to synthetic material apt to stably absorb high quantities of heparin. However, there is no teaching nor suggestion in Meisner, Nimni, or Barbucci of any biocompatible macromolecular membrane composition or of the binding agent or linker molecule or uses and embodiments or structures of the composition of the present invention; and therefore these documents, either individually or in any combination fail to teach or suggest the present invention.
Rase, et. al, U.S. Pat. No. 5,169,631, relates to a topical antimicrobial composition containing an antimicrobial agent wherein the wall of the microcapsule is formed from cross-linking collagen and a GAG by a cross-linking agent. Yannas, et al., U.S. Pat. No. 4,955,893, is directed to biodegradable polymers of uncrosslinked or crosslinked collagen-GAG. Collombel, et al., U.S. Pat. No. 5,166,187, relates to a material having a base mixture of collagen, acetylated chitosan, and a GAG. Noishiki, et al., U.S. Pat. No. 4,704,131, relates to a material containing heparinized collagen bound to a GAG. There is no teaching or suggestion in Rase, Yannas, Collombel, or Noishiki of any biocompatible macromolecular membrane composition or of the binding agent or composition structures and uses of the present invention; and therefore, these documents, either individually or in any combination fail to teach or suggest the present invention.
Huc, et al., U.S. Pat. No. 5,071,436, relates to a collagen hydroxy-apatite bound to a GAG composition. Stone, U.S. Pat. Nos. 5,108,438, 5,116,374, and 5,258,043 is directed to a meniscus which has dry, porous, volume matrices of fibers wherein GAG can be interspersed in the fibers for cross-linking. There is no teaching nor suggestion in Huc or Stone of any biocompatible macromolecular membrane composition, or of the binding agent or composition structures or uses of the present invention; and therefore, these documents, either individually or in any combination, fail to teach or suggest the present invention.
Chu, et al., U.S. Pat. No. 5,024,841, relates to a collagen implant formed from collagen fibrils. Benitz, et al., U.S. Pat. No. 4,945,086, relates to an epithelium-derived inhibitor of the growth of smooth muscle cells, along with methods for purifying such substance. As initially isolated, the inhibitor can be a heparin sulfate proteoglycan which releases a GAG chain on protease cleavage. Gallo, et al., U.S. Pat. No. 5,129,877, relates to a delivery system for biologically active materials consisting of polysaccharide or polypeptide microspheres which bind to a GAG receptors on cell surfaces. There is no teaching nor suggestion in Chu, Benitz, or Gallo of any macromolecular membrane composition, or of the binding agent or composition structures or uses of the present invention; and therefore, these documents, either individually or in any combination fail to teach or suggest the present invention.
Cristofori, et al., U.S. Pat. No. 5,252,339, relates to an oral pharmaceutical composition coated by an enterosoluble gastroresistant film containing a lyophilizate consisting of therapeutically effective amounts of a GAG, a thickening substance and surfactants and process for obtaining them. Huc, et al., U.S. Pat. No. 5,244,672, is directed to a composition containing liposomes which is stabilized by a stabilizing support comprising a mixture of atelocollagen and a GAG. However, there is no teaching nor suggestion in Cristofori or Huc of the macromolecular membrane composition, or the binding agent of the present invention; and therefore, these documents, either individually or in any combination fail to teach or suggest the present invention.
It can therefore be appreciated that there is a long-felt need for a non-immunogenic, biocompatible macromolecular membrane composition, particularly of such a composition in which the membrane is a cellulose membrane to which GAG is covalently surface bound through a linker agent, especially such a membrane composition in the form of a pouch containing an active ingredient such that molecules selectively pass into and out of the pouch; and, that there is a long-felt need for methods of making and using such a membrane.
Indeed, not only for implantation (cutaneous or any degree subcutaneously) or any in vivo setting, but also for in vitro and ex vivo applications there has been a long-felt need for the present invention and methods thereof. For instance, in vitro cell culturing for either harvesting cell product or harvesting the cells themselves, for instance for readministration (ex vivo), or simply harvesting using conventional media, dishes or broths presents a plethora of avenues by which non-biocompatible or immunogenic molecules or contaminants may be introduced to the cells or any harvest therefrom. Such cells can be antibody-producing cells for harvesting binding molecules, e.g., antibodies or cells such as post-stimulated or antigen-exposed cells, or cells which produce a needed biomolecule such as a hormone, e.g., insulin, i.e., islet of Langerhans cells. By either culturing over or within a preferably cellulosic selective membrane pouch to which glycosaminoglycan is bound, as in the present invention, such deficiencies of conventional dishes, media and broth are diminished.
Also, mention is made that cross-linked compositions in the literature provide for a rigid membrane. Non-cross linkage, for instance, in preferred embodiments in the present invention, provide a significant departure from that which has not been heretofore, for instance, a flexible membrane such as a pouch, suitable for implantation or other use in vitro in virtually unlimited locations.